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1、,TAM302Engineering Design Principles,Syllabus Topic:DFMA Feature Based Costing,Course Instructor:Mike PhilpottDirector of Concurrent Design&Manufacture LabAssociate Professor of Mechanical Science&Engineeringmphilpotuiuc.edu,netfiles.uiuc.edu/mphilpot/www/TAM302.html,Piece-part costs,Tooling costs,A
2、 simple fork end for Pneumatic Piston,Production Volume:Recurring Costs versus Non-Recurring Costs,Machine from Solid,Welded Assembly,Casting,Extrusion or Stock Channel,Sheet Metal,Injection Mold,Cost Estimating from Geometric Features,DTC/DFM Background,1990s DFMA software stand alone software base
3、d on MTM standard times and empirical models(e.g.Boothroyd and Dewhurst)Designers needed to know cost early in design to do what-if analysis and explore alternative designs before expensive hard tooling decisions finalizedAdvent of solid modeling with access to full solid definition of the part and
4、assemblyDesign to Cost(DTC)strategies in place,due to high overseas competition,but no practical toolsNeed to know early if cost targets are being met-redesign if necessary before its too late.,Feature Based Costing(FBC)TMA DFM Cad-based tool,Estimating cost directly from a part models geometric fea
5、turesIn real-time during CAD modeling with little to no extra time and without expert manufacturing knowledgeIn an integrated environment with direct access to enterprise cost data(e.g.updated material cost,machine parameters,labor rates,overhead rates etc.),FBC Technology Patents at UIUC,Granted:Ph
6、ilpott,M.L.et al,“Integrated Real-Time Feature Based Costing(FBC),”provisional filed U.S.Patent Office,Nov.2003,granted U.S.Patent No.7,065,420,June 20,2006.Assignee:University of Illinois at Urbana-ChampaignPending:Philpott,M.L.et al,“System and Methods for Determining Costs within an Enterprise,”6
7、0/523,746,filed U.S.Patent office,Nov 2007.Philpott,M.L.et al,“Template framework for automated process routing,”3810.1002-001,filed U.S.Patent office,Nov 2010.,CAD-integrated feature recognition and extraction methodology to provide engineers with accurate real-time cost feedback during design.,Geo
8、metric Cost Drivers,Physics Based Mechanistic Manufacturing Process Models(cycle times-cost),Times and Costs,Non-Geometric Cost Drivers,CAD Solid Model,feature extraction algorithms,1.Cost Scripting Language2.Parameterized machine,material,tooling and labor Database,Optimum manufacturing sequence au
9、tomatically derived from CAD Solid Model based on deterministic routing logic and Genetic Algorithms,real-time cost feedback loop,Routing Engine,User,Feature Based Costing(FBC)Research,In-House,Supplier,Virtual Production Environments,Industry/University Collaborative research project:UIUC/John Deer
10、e 6 year duration-technology now being commercialized*,“Integrated Real-Time Feature Based Costing(FBC),”U.S.Patent No.7,065,420,June 20,2006,*,Integration with commercial CAD systems incl ProE,Catia,NX,Inventor&Solidworks.,Integration to CAD,Results at John Deere on Sample of 71 parts,Feature extra
11、ction algorithms are used to search for the sequence of processes and routings that minimizes the cost of manufacture of individual parts or assemblies of parts.,Feature Based Costing(FBC)Implementation,Commercialization Startup(www.aP)with user base now including:Deere,CAT,JLG,Eaton,Dana,Excel,AGCO
12、,Polaris,Volvo Trucks,Value to Customer,High,Low,Low,High,Profit to Company,Form,Promote Cost as a True Parameter of Design,(the 4th F?),Cost Accounting Taxonomy,Total Fully Burdened Cost,Non-Recurring Costs,Mechanistic Cost ModelsEg.Laser Process Model,LaserCycleTime=Cutting Time+Piercing Time+Rapi
13、d Traverse Time+Scrap Cut Time,Laser Cycle/Labor Time,LaserLaborTime=LaserCycleTime*LaborStandard,BendCycleTime=LoadTime+NumBends*(1/BendRate)+ManipulationTime*(NumBends-1)+UnloadTimeBendLaborTime=BendCycleTime*LaborStandard,Bend Brake Cycle/Labor Time,Labor Cost=LaserLaborCost+BendLaborCost LaserLa
14、borCost=LaserCycleTime*LaserLaborRate BendLaborCost=BendCycleTime*BendLaborRate,Total Labor Cost,Total Direct Overhead Cost,OverheadCost=LaserOverheadCost+OverheadLaborCost LaserOverheadCost=LaserLaborTime*LaserOverheadRateBendOverheadCost=BendLaborTime*BendOverheadRate,Material Composition File,Mat
15、erial Stock Table,Machine Table,Laser Cut Rate Table,Injection Molding Movie Link,Injection Molding,1.Mold Closes,2.Inject Plastic,3.Cooling Time,4.Mold Opens,The Mold(Tooling),Moving Side Cores or Slides,Moving Internal Cores or Lifters,Avoiding Moving Side Cores and Lifters(1),Avoiding Moving Side
16、 Cores and Lifters(2),Injection Molding,See full spreadsheet on class website:Plastics_materials.xls,STEP 1 Material Cost,STEP 1 Material Cost(continued)Material Cost=Part Weight x CostPerKg/Material UtilizationWeightFor new parts:get volume from ProE,Density from spreadsheet,and compute weight.For
17、existing parts:weigh the parts.Cost/KgDecide on material,and lookup using Plastics_materials.xls Material UtilizationAssume 98%utilization for regular injection molding of plastics.High because most of runners and scrap parts can be remelted.,STEP 2 Labor Time(&Cycle Time)In Injection molding,Cycle
18、time is the total time from start to finish of the molding cycleLabor Time=Cycle Time*Labor Ratio(usually one operator tending 2 or more machines)Cycle Time=Injection Time+Cooling Time+Ejection Time1.Injection TimeInjection time is the time to fill the mold with plastic.A reasonable approximation of
19、 this:Injection Time=(Part Volume+10%additional for Runner Volume)*number of cavities/Injection Ratewhere Injection Rate=Max Injection Rate of the machine*0.8 Assumptions for Machine Selection(ref:Injection_Molding_Machines.xls):1.Smallest machine is most cost effective2.Number of Cavities in the mo
20、ld determined by smallest machine(else single cavity)3 The machine must have sufficient Press Force4.The mold must fit on the machine Distance between tie bars5.The machine must have sufficient Injection Capacity,STEP 2 Labor Time(&Cycle Time)-continuedDetermine machine size and number of cavities:1
21、.Measure the smallest enclosing rectangle(SER)parallel to the parting line2.Add 1”(25mm)border around the part to allow for runners etc3.Will this fit on the smallest machine(ie.Distance between tie bars)?Yes how many cavities?,No find machine that it will fit on,and use multi-cavity if aspect ratio
22、 works.Compute Press Force Required:Press Force=Projected Area of part*number of cavities*safety margin*Clamping Pressure(see Plastics_materials.xls for required clamping pressure)Assume safety margin=1.3(i.e.30%safety factor)Check Injection Capacity:Shot Size=(Part Volume+10%additional for Runner V
23、olume)*number of cavities.Check machines injection capacity,if too small reduce number of cavities and/or bigger machine.Identify injection molding machine used,STEP 2 Labor Time(&Cycle Time)-continued2.Cooling Time:Cooling time is the time for the mold to cool sufficiently to eject without damage,P
24、max_thickness=Max thickness of the part ThDiffusivity=Thermal Diffusivity for the materialTdeflect=Eject Deflection temperature for the materialTmold=Mold temp for the materialTmelt=Melting temp for the material,3.Ejection Time:The time to open the mold,eject the part,and close the mold again.This i
25、s approximately equal to the dry cycle time for the machine,STEP 3 Compute Piece Part CostThe cycle time drives these two important cost elementsCycle Time per part=Cycle Time/number of cavitiesLabor Time per part=Cycle Time per part*labor ratioMaterial Cost:from Step 1Labor Cost=Labor Time per part
26、*Labor Rate($/hr)Direct Overhead Cost=Cycle Time per part*Overhead Rate($/hr)Setup Cost=Setup Time*(Labor Rate+Overhead Rate)/(Annual Volume*Number of parts per product/Number of batches per year)Values and assumptions based on your Product Development Spec(PDS)So:Piece Part Cost=Material Cost+Labor
27、 Cost+Overhead Cost+Setup Cost,STEP 4 Compute Hard Tooling CostHard Tooling Cost=Use IPLAS Tooling Cost Estimator on class website,Amortization Volume=Annual Production Volume*Number of Parts per product*Product LifeTooling Cost per Part=Hard Tooling/Amortization Volume,STEP 5 Total Cost per PartRec
28、urring Costs:Total Cost per Part=Piece Part Cost+Tooling Cost Per PartNon-Recurring Costs:Investment in Molds and Dies=Hard Tooling Cost,Polypropylene(1.5/cu.in):Outstanding resistance to flex and stress cracking.Excellent chemical resistance and electrical properties.,Good impact strength above 15F
29、.Good thermal stability,light weight,low cost.Some grades can be electroplated.,Polystyrene(1.7/cu.in):Low cost,easy to process,rigid,crystal-clear,brittle.Low moisture absorption,and heat resistance.Poor outdoor stability.,Polyethylene-HDPE&LDPE(1.2/cu.in)Lightweight,easy to process,low cost materi
30、al.Poor dimensional stability and heat resistance.Excellent chemical resistance and electrical properties.,4,LDPE,2,HDPE,Common Thermoplastic Materials(1),5,PP,6,PS,PVC(2.2/cu.in):Rigid grades are hard,tough,and have excellent electrical properties,outdoor stability,and resistance to moisture and ch
31、emicals.Flexible grades are easier to process but have lower properties.Heat resistance is low,and low cost.,ABS(2.9/in3):Very Tough,hard,and rigid.Fair Chemical resistance.Low Water absorption and good dimensional stability.High abrasion resistance.Some grades are easily electroplated.,Acrylic(3.1/
32、cu.in)Hard,glossy surface and high optical clarity.Fair Chemical resistance.Excellent resistance to outdoor weathering.Available in brilliant,transparent colors.Excellent electrical properties.,Common Thermoplastic Materials(2),3,V,PETE(4.9/cu.in)Crystal clear and hard.Used widely for shampoo bottle
33、s.Good moisture,and chemical resistance.Good dimensional stability.,Acetal(5.8/cu.in)Very Strong,stiff,and low tendency to stress crack.High resistance to chemicals.Retains most properties when immersed in hot water.Exceptional dimensional stability.High abrasion resistance.Low coefficient of Fricti
34、on.,Polyurethane(6.1/cu.in)Tough,extremely abrasion and impact-resistant.Good electrical properties and chemical resistance.UV exposure causes brittleness,lower properties,and yellowing.,PETE,1,Common Thermoplastic Materials(3),Other,7,Fluoroplastics(30-65/cu.in):PTFE,FEP,PVDF etc.Family of high cos
35、t,low-to-moderate strength.Excellent chemical resistance.Low Friction.Outstanding stability at high temperatures.,Polycarbonate(6.3/cu.in):Highest impact resistance of any rigid,transparent plastic.Excellent outdoor stability and resistance to creep under load.Fair chemical resistance.Some aromatic
36、solvents cause stress cracking.,Nylon(6/6-5.9/cu.in;6/12-9.0/cu.in;+glass-16.3/cu.in):Family with outstanding toughness and wear resistance.Low Coefficient of Friction.Excellent chemical resistance and electrical properties.Hygroscopic;dimensional stability is poor.Some grades are electroplatable.,C
37、ommon Thermoplastic Materials(4),MoldCoster by IPLAS.htm,Sheet Metal Parts Progressive Die,See spreadsheet on class website for more details:SheetMetalMaterial.xls,STEP 1 Material Cost,Sheet Metal-Progressive Dies,Progressive Die in Operation 30 ppm,Progressive Die in Operation 100 ppm,STEP 1 Materi
38、al Cost(continued)Progressive die machines are fed from coil stock.Quite a bit of waste that has no real$value.so assume lost.Material Cost=Blank Weight x Cost/Kg/Material UtilizationCoil Width and Part Pitch1.Need the SER(smallest enclosing rectangle of the flat pattern or unfolded form.If modeled
39、in ProE,may be able to get this automatically.Else,estimate by measurement.2.Coil width=blank width+1/4”each side for carrier strip3.Part Pitch=blank Length+”for pilot holesBlank WeightBlank volume=coil width*part pitch*thicknessCost/KgDecide on material,and lookup using in tableMaterial Utilization
40、Assume 100%utilization here as we are accounting for most of the scrap through the blank computation.1-2%waste from end of coils may sometimes be included.,STEP 2 Cycle Time Much easier than injection molding!Cycle Time Per Part=Press Cycle time/%UPtimeRules for Machine Selection:1.The progressive d
41、ie set must fit on the press bed:Part width max die width,and Part Pitch*number of stations max die length2.Use smallest press possible(note:see tooling cost section for number of stations),STEP 3 Compute Piece Part CostLabor Time=Labor Ratio*Cycle Time per part Labor Cost=Labor Time*Labor Rate($/hr
42、)Direct Overhead Cost=Cycle Time per part*Overhead Rate($/hr)Setup Cost=Setup Time*(Labor Rate+Overhead Rate)/(Annual Volume*Number of parts per product/Number of batches per year)Add Painting(if applicable):Paint Cost=Surface area of part*$/m2So:Piece Part Cost=Material Cost+Labor Cost+Overhead Cos
43、t+Setup Cost+Paint Cost,STEP 4 Compute Hard Tooling Cost1.Computing Number of Stations:Pilot Station:Always 1 Blanking Station:Always 1Piercing Station:1 if internal cut features or holes presentNumber of Bending Stations:Starting from the main surface(original blank),countthe maximum incremental nu
44、mber of bends on bends.For each bend over 90 degrees,add another increment.Number of Forming stations:One for each direction(a form is a contoured depression)Number of Draw stations:One for each direction(a deep contoured depression 4:1 width to depth of depression)2.Use DieCost.xls spreadsheet to c
45、ompute the tooling cost for the die base and additional cost for each stationDieBaseCost:use Die area(Part Width*Part Pitch*number of stations)BlankingCost:Perimeter of partPiercingCost:Perimeter of holesBendingCost:length of bendsFormingCost:surface area of formsDrawCost:surface area of draws(depth
46、 4:1),STEP 4 Compute Hard Tooling Cost(continued)Hard Tooling Cost=DieBaseCost+BlankingCost+PiercingCost+BendingCost+FormingCost+DrawCostAmortization Volume=Annual Production Volume*Number of Parts per product*Product LifeTooling Cost per Part=Hard Tooling Cost/Amortization Volume STEP 5 Total Cost
47、per PartRecurring Costs:Total Cost per Part=Piece Part Cost+Tooling Cost Per PartNon-Recurring Costs:Investment in Molds and Dies=Hard Tooling Cost,Die Casting,Costing Die Cast Parts,See full spreadsheet on class website:DieCastingMaterials.xls,STEP 1 Material Cost,STEP 1 Material Cost(continued)Mat
48、erial Cost=Part Weight x Cost/Kg/Material UtilizationWeightDecide on material composition,get volume from ProE,density from DieCastingMaterials.xls,and compute weightCost/Kglookup using DieCastingMaterials.xlsMaterial UtilizationAssume 95%utilization for die casting.High because most of runners and
49、scrap parts can be remelted.,STEP 2 Labor Time(&Cycle Time)Cycle time is the total time from start to finish of the casting cycle For Die Casting Process:cycleTime=dieCloseTime+ladleTime+injectTime+coolTime+dieOpenTime+partRemovalTime+lubeTime+trimTimeRules for Machine Selection(ref:dieCastingMachin
50、e.xls)1.Assume a single cavity mold2.Smallest machine is most cost effective(lowest overhead rate)3.The mold must fit in the casting machine(tie bar length/width and mold thickness)4.The machine must have enough Force capability(see press force calc section)Using the date from ProgressiveDieMachines
